/**
数字运算符：
    1. + 
    2. -
    3. *
    4. /
    5. %
*/

.container {
    /* ==================+ 运算===================== */
    width: 50 + 20; //70
    width: 50 + 20%; //70%
    width: 20% + 70%; //90%
    width: 10px + 20px; //30px
    width: 10px + 10pt; //23.3333333333px;
    width: 10px + 10; //20px
    /* ==================- 运算===================== */
    width: 50 - 20; // 30
    width: 50 - 20%; // 30%
    width: 20% - 10%; //10%
    width: 20px - 10px; //10%
    width: 20px - 10pt; //6.6666666667px;
    width: 20px - 10; //10%
    /* ==================* 运算===================== */
    width: 10 * 20; //200
    width: 10 * 20%; //200%
    width: 10 * 20px; //200px
    width: 10 * 20pt; //200pt
    /* ==================/ 运算===================== */
    width: 10 / 5; //10/5
    width: (10 / 5); //2
    width: 10px / 5px; //10px/5px
    width: 10px / 10 *2; //2px
    width: round($number: 10)/2; //5
    $width: 100px;
    width: ($width / 2); //50px
    /* ==================% 运算===================== */
    width: 10 % 3; //1
    width: 50 % 3px; //2px
    width: 50px % 4px; //2px
    width: 50px % 7; //1px
    width: 50% % 7; //1%
    width: 50% % 9%; //5%
    width: 50px % 10pt; // 10px
    width: 50px % 13.33333px; //10.00001px
    width: 50px + 10pt; //63.3333333333px
    /* ==================+ 运算===================== */
    content: "Foo" + bar;//"Foobar"
    content: Foo + "bar";//Foobar
    content: Foo + bar;//Foobar
    content: "Foo" + "bar";//"Foobar"
}